Modern environmental concerns and regulations impose significant requirements for removing contaminants and undesirable constituents from the exhaust flow discharged into the ambient environment from industrial and other commercial operations. In some cases, the discharged exhaust flow must be cleaned or otherwise conditioned before it may it is discharged. For example, food preparation establishments are now required, or will soon be required, to remove the relatively high concentrations of smoke and fat airborne contaminants from the cooking exhaust. Not only is smoke generated while cooking the food, but particulate matter such as grease and fat and volatile contaminants such as odor are also created. Moreover, the hydrocarbon fuels which are burned while cooking the food generate carbon monoxide, which is toxic and may be lethal in concentrated doses. Other examples of business and industrial operations which generate exhaust with offensive and toxic particulate and gaseous contaminants are automobile repair shops, clothes drycleaning operations, and waste and water treatment plants.
Industrial and business operations frequently discharge the exhaust flow from the confined interior environment of the establishment into the ambient environment outside of the establishment. Usually the exhaust consists not only of the smoke, odor, particulates, volatile organic compounds, carbon monoxide and other toxic gases, but also air drawn from within the confined environment of the establishment which is used to carry these contaminants outside of the establishment and into the ambient environment. Some types of these industrial and business operations, such as restaurants or food preparation establishments, generate a relatively large amount of such contaminants, and the amount of air consumed from within the confined environment to exhaust the contaminants is substantial. Makeup air must be admitted into the confined environment of the establishment to replace the air consumed by the exhaust flow.
The amount of makeup air required to replace the air of the exhaust flow is usually a significant portion of the overall air required to condition the interior confined environment of the establishment. Because the interior air used in the exhaust flow is drawn from the heated, cooled or otherwise conditioned air or within the interior confined environment, the makeup air admitted into the confined environment to replace the exhaust air flow must also be heated, cooled or otherwise conditioned. Otherwise, the desired thermal environment within the establishment could not be maintained. Of course, the thermal energy content of the air within the exhaust flow is when the exhaust flow is discharged into the ambient environment.
The energy required to heat, cool or otherwise condition makeup air may be a significant operating cost of the establishment. For example, the size and energy consumption of the heating and cooling equipment required to condition the makeup air for a small fast food restaurant is approximately four times the size and capacity that would be otherwise required if air was not withdrawn from within the interior of the confined environment as part of the cooking exhaust flow into the ambient environment. Considerable expense is involved in obtaining the increased capacity of the heating and cooling equipment for conditioning the makeup air, and in operating that equipment.
One of the significant drawbacks to recirculating the exhaust air from confined environments such as food preparation establishments, has been an inability to clean the contaminants from the exhaust air in a cost-efficient manner. The previous invention referenced above offers a relatively low cost and highly effective solution of ridding the exhaust air of particulate and gaseous contaminants, thus offering the possibility of recirculating the cleaned and benign exhaust flow back into the confined environment.
It is with respect to these and other considerations that the present invention has evolved.